Last Updated: May 2026
Chapter 6: Life Processes is the cornerstone of CBSE Class 10 Science Biology section — typically worth 10-12 marks in the board exam. The chapter covers the four life processes that maintain living organisms: nutrition, respiration, transportation, and excretion. CBSE 2027 candidates need to master both diagrams and process flow because diagram-based 3-mark and 5-mark questions appear in every paper. This is the complete NCERT-aligned guide.
Snapshot — Chapter 6 Life Processes
| Parameter | Detail |
|---|---|
| NCERT Chapter | Class 10 Science Chapter 6 |
| Average Board Marks | 10-12 |
| Diagrams to learn | Heart, alveoli, nephron, leaf cross-section, stomata |
| Sub-topics | Nutrition, Respiration, Transportation, Excretion |
1. Nutrition
Autotrophic Nutrition (Photosynthesis in Plants)
Equation: 6CO₂ + 6H₂O → (in presence of sunlight and chlorophyll) → C₆H₁₂O₆ + 6O₂.
Site: Chloroplast (in mesophyll cells of leaves).
Conditions: Sunlight, chlorophyll, CO₂, water.
Stomata: Tiny pores on leaf surface; opening regulated by guard cells. Open during day for gas exchange.
Heterotrophic Nutrition
- Holozoic: Whole food taken in (humans, frogs).
- Saprophytic: Dead matter (mushrooms, bread mould).
- Parasitic: Lives on/in host (Cuscuta, tapeworm).
Human Digestive System
Mouth → Oesophagus → Stomach → Small Intestine → Large Intestine → Rectum → Anus.
Enzymes by location:
- Mouth — salivary amylase (digests starch).
- Stomach — HCl + pepsin (digests proteins).
- Pancreas → small intestine — pancreatic amylase, trypsin, lipase.
- Liver — bile (emulsifies fats).
- Small intestine — final digestion + absorption via villi.
2. Respiration
Types of Respiration
| Type | End Product | Energy |
|---|---|---|
| Aerobic respiration | CO₂ + H₂O | ~38 ATP per glucose |
| Anaerobic in yeast | Ethanol + CO₂ | ~2 ATP |
| Anaerobic in muscles | Lactic acid | ~2 ATP |
Human Respiratory System
Nostrils → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli (gas exchange).
Diaphragm: dome-shaped muscle that contracts during inhalation (flattens) and relaxes during exhalation.
Alveoli: 300 million in human lungs, providing 100 m² surface area.
Plant Respiration
Plants respire 24×7. Gas exchange via stomata (leaves) and lenticels (stems).
3. Transportation
Human Circulatory System
Heart: Four-chambered (2 atria + 2 ventricles). Mammals and birds have complete double circulation.
Pulmonary circulation: Right ventricle → Pulmonary artery → Lungs → Pulmonary vein → Left atrium.
Systemic circulation: Left ventricle → Aorta → Body → Veins → Right atrium.
Blood Components
- Plasma — fluid matrix (55%).
- RBCs — carry oxygen via haemoglobin.
- WBCs — immunity.
- Platelets — clotting.
Blood Vessels
| Type | Direction | Wall | Valves |
|---|---|---|---|
| Arteries | Heart → body | Thick, elastic | None (pulmonary artery has) |
| Veins | Body → heart | Thin | Yes (prevent backflow) |
| Capillaries | Linking | Single cell thick | None |
Plant Transport
- Xylem — water and minerals from roots to leaves. Driven by transpiration pull.
- Phloem — food (sugars) from leaves to all parts. Bidirectional. Driven by pressure flow / translocation.
4. Excretion
Human Excretory System
Kidneys (2) → Ureters → Urinary bladder → Urethra. Each kidney has ~1 million nephrons — the functional unit.
Nephron Structure
Bowman’s capsule + glomerulus = filter. Tubule reabsorbs water, glucose, salts. Final urine collects in collecting duct.
Plant Excretion
- Gaseous waste (O₂, CO₂) — through stomata/lenticels.
- Excess water — transpiration.
- Waste products — stored in vacuoles, gums, resins, leaves before fall.
5. Diagrams to Practise (5-mark Questions Often Demand These)
- Cross-section of a leaf — palisade, spongy mesophyll, stomata, xylem, phloem.
- Human heart — 4 chambers, 4 valves, aorta, pulmonary artery and vein, vena cava.
- Alveoli — capillary network, gas exchange.
- Nephron — Bowman’s capsule, glomerulus, PCT, loop of Henle, DCT, collecting duct.
- Stomata with guard cells — open and closed states.
30 Important Board Exam MCQs — Sample of 10
Q1. The site of photosynthesis is — (a) Mitochondrion (b) Chloroplast (c) Ribosome (d) Vacuole. Ans: (b)
Q2. Which of these is the longest part of the alimentary canal? (a) Mouth (b) Oesophagus (c) Small intestine (d) Large intestine. Ans: (c)
Q3. The end product of anaerobic respiration in muscles is — (a) Ethanol (b) CO₂ (c) Lactic acid (d) Pyruvate. Ans: (c)
Q4. The functional unit of the kidney is — (a) Neuron (b) Nephron (c) Alveolus (d) Glomerulus. Ans: (b)
Q5. Translocation of food in plants takes place through — (a) Xylem (b) Phloem (c) Cambium (d) Meristem. Ans: (b)
Q6. Which gas is released during photosynthesis? (a) CO₂ (b) O₂ (c) N₂ (d) H₂. Ans: (b)
Q7. Bile is secreted by — (a) Pancreas (b) Liver (c) Stomach (d) Gall bladder. Ans: (b) Liver (stored in gall bladder).
Q8. The pulmonary artery carries — (a) Oxygenated blood (b) Deoxygenated blood (c) Lymph (d) Plasma. Ans: (b)
Q9. Which structure prevents backflow of blood? (a) Valves in veins (b) Capillaries (c) Atria (d) Aorta. Ans: (a)
Q10. Plants excrete via — (a) Gums and resins (b) Sweat glands (c) Kidneys (d) Lungs. Ans: (a)
Frequently Asked Questions
How many marks does Life Processes carry in CBSE Class 10?
10-12 marks across MCQs, short answers and at least one 5-mark long-answer (often diagram-based on the heart or the nephron).
Is the heart diagram compulsory?
A 5-mark question with a heart, nephron or leaf cross-section diagram appears in 80% of board papers. Practise drawing all five diagrams from memory.
Best way to memorise the digestive enzymes?
Make a table: location → enzyme → substrate → product. Write it 5 times across one week. The enzyme-substrate-product chain is asked as 3-mark short answer.
Why are plants slow at transport compared to animals?
Plants do not have a pumping organ like the heart. Transport is driven by passive forces — transpiration pull in xylem and source-to-sink pressure in phloem.
Recommended book for revision?
NCERT Class 10 Science is the spine. Supplement with Lakhmir Singh & Manjit Kaur Biology and the previous 5 years’ CBSE Sample Papers.
